1. Field of the Invention:
The present invention relates to a method of remodelling large-sized special ships or vessels such as an aircraft carrier, a large-sized catamaran, an offshore structure and so forth and, more particularly, to a method of attaching a blister to the hull of such a ship or a structure in a dry dock.
2. Description of the Prior Art:
It is a common measure to improve the buoyancy or the stability of a vessel by attaching blisters or bulges to the ship's sides.
The attaching of the blister or the bulge is conducted while the ship is situated in a dry dock. The work for attaching a blister or bulge, however, encounters a problem particularly when the ship is a large-sized and specially shaped one, e.g., an aircraft carrier Namely, in such a case, it is very difficult to access the lower portion of the hull vertically from the upper side of the ship and the working space is seriously limited, partly because the clearance between the hull and the wall of the dock is very small and partly because an upper structure such as a flight deck projects laterally above the banks of the dry dock. In case of a large-sized catamaran, the upper structure such as house makes it difficult to access the lower portion of each hull, thus causing an impediment to the work for attaching blisters.
Due to these difficulties, the work for attaching blisters to such specially-shaped large-sized ships has been conducted either by a method in which the blister is divided into a plurality of small sections which are brought to the ship's side one by one by means of, for example, chain blocks and assembled one after another to complete the blister on each side of the ship's hull, or by a method in which obstacles such as the flight or upper deck or other obstacles projecting laterally from the deck are temporarily removed and the blister as an assembly is lowered by a crane such as a goliath crane to a position where it faces the ship's side, through the clearance formed after the removal of the obstacle, followed by remounting of the obstacles after the attaching of the blister.
The first-mentioned method, however, requires a long time and the efficiency of the work is inevitably lowered due to the fact that most of the work has to be done by manual labour. The first-mentioned method also requires the use of scaffolds and platforms, which is rather inconvenient from the view point of safety.
On the other hand, the second-mentioned method requires additional work for removing the obstacles projecting from the flight or upper deck, as well as remounting of the same after the attaching of the blister. Thus, much labour and long time are spent for works other than the work for attaching the blister.